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Effects of recruitment of collapsed lung units on the elastic pressure–volume relationship in anaesthetised healthy adults
Author(s) -
Svantesson C.,
Sigurdsson S.,
Larsson A.,
Jonson B.
Publication year - 1998
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1998.tb05268.x
Subject(s) - medicine , insufflation , compliance (psychology) , pulmonary compliance , linear relationship , volume (thermodynamics) , anesthesia , lung volumes , respiratory system , lung , anatomy , mathematics , psychology , social psychology , statistics , physics , quantum mechanics
Background: The elastic pressure–volume (P el –V) curve of the respiratory system can be used as a guide for improved ventilator management. The understanding of curves recorded for sick patients can be improved with better knowledge of the P el –V relationship observed in healthy humans. Dynamic P el –V curves were determined over an extended volume range in 15 anaesthetised and muscle‐relaxed healthy humans. The influence of a recruitment manoeuvre was studied. Methods: Dynamic P el –V curves were determined during a single prolonged insufflation before and after the recruitment manoeuvre. A mathematical three‐segment model of the curve including a linear intermediate segment, delineated by the lower (LIP) and upper (UIP) inflection points, was used for characterisation of the recorded curves. Results: The model gave an adequate description of the recorded P el –V curves. Before the recruitment manoeuvre, compliance increased until the LIP was reached at 20 cm H 2 O (1.9 L). Then followed a long linear segment. After the recruitment manoeuvre, compliance increased during insufflation until a LIP was reached at 13 cm H 2 O (1.2 L). Above the LIP followed a shorter linear segment (compliance = 140 mL/cm H 2 O) and then an upper segment with decreasing compliance. Conclusion: P el –V curves recorded before and after the recruitment manoeuvre show that large lung compartments close during anaesthesia and that high pressures are needed to achieve recruitment even in the normal lung. Accordingly, the LIP does not define the end of recruitment during insufflation.